go: Add convenient construction of rawPayload messages (#1538)

Part of svix/monorepo-private#9470.

Author: svix-jplatte

go/message.go

@@ -96,3 +96,31 @@ func (m *Message) ExpungeContent(ctx context.Context, appId string, msgId string
 	res, err := req.Execute()
 	return wrapError(err, res)
 }
+
+// Instantiates a new MessageIn object with a pre-serialized payload.
+//
+// The payload is not normalized on the server. Normally, payloads are required
+// to be JSON, and Svix will minify the payload before sending the webhook
+// (for example, by removing extraneous whitespace or unnecessarily escaped
+// characters in strings). With this function, the payload will be sent
+// "as is", without any minification or other processing.
+//
+// The `contentType` parameter can be used to change the `content-type` header
+// of the webhook sent by Svix overriding the default of `application/json`.
+//
+// See the class documentation for details about the other parameters.
+func NewMessageInRaw(eventType string, payload string, contentType openapi.NullableString) *MessageIn {
+	msgIn := openapi.NewMessageIn(eventType, make(map[string]interface{}))
+
+	transformationsParams := map[string]interface{}{
+		"rawPayload": payload,
+	}
+	if contentType.IsSet() {
+		transformationsParams["headers"] = map[string]string{
+			"content-type": *contentType.Get(),
+		}
+	}
+	msgIn.SetTransformationsParams(transformationsParams)
+
+	return msgIn
+}